Preheat the oven to 425F/218C. Line a large baking sheet with parchment paper or a silicon baking mat. Also, prepare a large pastry bag tipped with a star tip; I used Ateco tip #847.

Prepare the pate a choux dough first. In a small saucepan, combine the water, salt and butter. Cook the mixture over medium-high heat until the butter is melted and the liquids come up to a simmer. Add the flour all at once and whisk, cooking for about 1 minute, until the batter comes together into a ball. Transfer the dough into a clean bowl (optional - can be prepared in the saucepan, too!). Allow the dough to cool for 10 to 15 minutes, until warm to touch.

Begin adding the eggs, one at a time, mixing very well after each addition. The dough will come together after adding the last egg. Transfer the batter into the prepared pastry bag. Pipe the dough onto the prepared baking sheet, forming 10 to 12 large dollops.

Bake the profiteroles in the preheated oven at 425F for 10 minutes, then turn the oven temperature down to 375F/190C. Continue baking for 35 to 40 minutes, until the profiteroles are a rich, golden brown color. Avoid opening the oven door, as this could cause them to fall flat. Once the profiteroles are baked, remove them from the oven and cool them completely on a wire rack.

Next, prepare the Nutella whipped cream (UPDATED instructions vary from the video!) Place the cream cheese, and Nutella into a mixing bowl and whisk for a 2 to 3 minutes until smooth and creamy. In a separate bowl, whisk together the whipped cream and confectioner's sugar. Add the Nutella mixture to the whipped cream, along with the salt and vanilla. Whisk for about 30 seconds, just until everything is incorporated; do not overmix. Transfer the cream into a large pastry bag tipped with a small, round tip.

To fill the profiteroles, insert the small piping tip into the top of each cream puff and pipe it full of cream. As you pipe the filling, you should feel the cream puffs expand slightly. Once all the cream puffs are filled, place them into the refrigerator to chill for 30 to 60 minutes.

To garnish the top with chocolate, place the dark chocolate chips into a medium bowl and heat until completely smooth (in microwave or over double-boiler). Dip the top of each cream puff into the melted chocolate, then set onto a wire rack to set. To garnish the top, add the diced hazelnuts before the chocolate is set.